Fluorescent lamp starter



Aug. 8, 1944. c. H. HODGKINS, 2,355,438

FLUORESCENT LAMP STARTER Filed Feb. 14, 1942 INVENTOR J5 (r11. f/ODG/f/ YS -25 L1 BY W WAIQ/KMHWL Patented Aug. 8, 1944 FLUORESCENT LAIHP STARTER Charles H. Hodgkins, Fairfield, Conm, assignor to The Bryant Electric Conn., a corporation of Company, Bridgeport, Connecticut Application February 14, 1942, Serial No. 430,887

Claims.

This invention relates to starting relays for fluorescent lamps, and more particularly to a relay of the thermal type which automatically operates to disconnect a failed lamp from the source of supply after a predetermined number of operations corresponding to a defining period of time.

Relays for the starting of fluorescent lamps are now extensively employed in the art. One of the disadvantages of such relays, heretofore, has resided in the fact that they have continued their cyclic operation of closing and opening a series heating circuit for the filamentary electrodes of the discharge lamp even when the lamp has failed. In many instances this causes a flickering of the lamp, which is a great source of annoyance to a user, and useless repetitious operagion of the relay naturally shortens its useful 11 c.

It is accordingly an object of the present invention to provide a starting relay for a fluorescent lamp which automatically operates to disconnect the lamp electrodes from the source in, the event the lamp fails.

Another object of the present invention is the provision of a starting relay of .the thermal type for starting a fluorescent lamp which automatically operates after a predetermined number of repetitious operations or lapse of a predetermined period of time to disconnect the lamp from the source of supply in the event the latter has failed for any reason.

A further object of the present invention is the provision of a thermal type starting relay for fluorescent, lamps which automatically operates after a predetermined number of repetitious operations and corresponding to a predetermined period of time to disconnect the lamp from the source upon failure of the lamp, and which relay can be reset upon replacement of the failed lamp with a new one.

Still further objects of the present invention will become obvious to those skilled in the art by reference to the accompanying drawing wherein: I Fig. 1 is a sectional view of the starting relay unit of the present invention and showing a front view'of the relay itself;

Fig. 2 is a fragmentary view taken at 90 to I that shown in Fig. g ,y-ng. 3 is a onthe line III-III of Fig. 1'

fragmentary sectional view taken Fig. is a view similar to Fig. 1, but showing the "locked-out or circuit opened position which it takes upon failure of a lamp.

Fig. 5 is a fragmentary sectional view taken on the line V-V of Fig. 4 and also showing the circuit opened position of the relay, and

Fig. 6 is a schematic diagram of a starting and energizing circuit for a fluorescent lamp employing a starting relay in accordance with the present invention.

Referring now to the drawing in detail, the starting relay of the present invention is shown generally at 5 and is housed within a metallic or plastic casing 6, together with a radio-frequency-suppressing condenser 1, both of which are connected in electrical parallel to a pair of socket terminals 8 and 9 adapted to engage a socket, and secured to an insulating closure member i0.

The relay itself comprises a base l2 of suitable insulating material such as fiber, a phenolic condensation product, hard rubber, or the like, and is provided with a rectangular opening i3 therein for a purpose hereinafter described. A substantially U-shaped heat-responsive element M in the form 01' a bimetallic memebr, is secured at the end of one of its legs to the base i2 and is connected by a metallic strap or the like I5 to the socket terminal 9, the latter of which is also connected by a conductor or the like It (Fig. 6) to one side of the condenser 1.

The end of the remaining leg of the U-shaped heat-responsive element It is provided with a contact member I! normally engaging a stationary contact member i8, carried by a strap or the like it disposed in an opening 20 with its end secured to the base I 2 and connected to the socket terminal 8 and to the remaining end of condenser I by a connecting strip 22 and conductor 23 on the rear of the base l2. As can be more readily seen from Fig. 2, the U-shaped heat-responsive element is provided with a corrugation 24 in its fixed leg near the base of the U, and

an electrical resistance heater 25 is secured to the base l2 beneath this corrugation with the ends of the heater being connected to a pair of socket terminals 26 and 21 similar to the terminals 8 and 9.

the-thermal relay of the present invention in Referring now more particularly to the schematic diagram of Fig. 6, it will be noted that when the relay unit is inserted in its socket, the heater 25 is connected in series with an inductance 28 and the discharge lamp 29, while the normally closed relay contacts l1 and I8 complete a series heating circuit for the filamentary electrodes 38 and 32 of the lamp 29. Accordingly, upon conerection of the lamp to the source of supply LiL2, which may be a transformer or a source of the customary domestic potential of approximately 115 volts, by closure of a switch 33, current will flow through the heater 23 and the illsmentary lamp electrodes 30 and 32, heating the latter to an electron-emitting temperature with the heater 25 being thus subjected to the full voltage of the source less the small voltage drop in the lamp electrodesand inductance, which will hereinafter be referred to as full line voltage.

By the time these electrodes have reached maximum electron-emitting temperature, the heater 23 will have heated the heat-responsive element or bimetallic member i4 sufficiently to cause the fixed leg to deflect toward the base l2 with the bottom of the U passing into the rectangular opening I3 provided for that purpose. Such deflection of the fixed leg causes deflect on of the remaining leg away from the base, thus separating the normally closed contacts i1 and II in the manner shown by the dotted lines in Fig. 3. Upon separation of these contacts, the series heating circuit for the lamp electrodes 30 and 32 is interrupted, and at the same time these preheated electrodes are subjected to a high voltage surge from the inductance 23 which initiates a discharge therebetween.

Once the discharge is initiated, the heater 25 is then subjected only to lamp voltage, which, although appreciably below full line voltage, nevertheless generates sufficient heat to maintain the heat-responsive element H in a heated condition with the contacts i1 and ll of the relay in an open position. If for any reason the discharge is not initiated on the first separation of the contacts I! and ii, the heater 25 no longer receives current due to the separation of the contacts i1 and IS, with the result that the heat-responsive element I4 cools, causing the contacts 11 and I3 to again close, thus reestablishing the series heating circuit for the lamp electrodes 30 and 32 as well as the heater 2!. This cyclic operation of the relay will continue until a discharge is finally initiated between the preheated lamp electrodes.

It is accordingly necessary that the relay perform this cyclic operation for the purpose of starting the lamp, but such requisite has, heretofore, also been a detriment where a lamp has failed due to deactivation of the electrodes because of the annoying flickering of the lamp and the continued operation of the relay which greatly shortens its useful life. To eliminate futile cyclic operation of the relay where a lamp has failed, the relay of the present invention is provided with a lock which operates to prevent further operation of the relay after a predetermined number of cyclic operations thereof corresponding to a predetermined period of time, or in other words, the relay operates to lock-out" the lamp whenever full line voltage is applied to the electric heater for an abnormal period of time.

To this end a latch arm 34 formed of suitable insulating material is pivoted to an eyelet or the like 35 which passes through the base I2 and interconnects the connecting strip 22 with the contact supporting strap is. This latch 34 is provided with an end forming a finger piece 36 protruding through a slot 31 in the closure l0, and its other end is provided with a tapered wedge 33 positioned so as to pass beneath the movable leg of the bimetallic member l4 and hold the contact i1 out of engagement with the contact I3, as hereinafter described.

A coil spring 33 has one of its ends anchored to a projecting pin 43 and its other end fastened to the latch arm 34 so as to be under tension preparatory to causing contra-clockwise rotation of the latch am about its pivot 35, as viewed from Fig. 1. To maintain the latch arm 34 in a normally inoperative position, the latter is provided with a pin or lug 4| protruding from its rear surface and thus disposed in the opening 20 provided in the base l2 of the relay 5. This lug 4| normally engages a second heat-responsive ele ment or bimetallic member 42 forming an extension of the strap i3 and anchored to the latter at its end which bears the contact |3.

If the discharge lamp 23 fails to start after several cyclic'operations of the relay 3, due to deactivation of the electrodes 33 or 32, the arcing occurring at the contacts I! and II together with repetitious application of full line voltage to the heater 25 will in a short period of time cause heating of the second bimetallic member 42, with the result that it deflects toward the back of the base l2 through the opening 23 therein, as shown more clearly in Fig. 5. Such deflection of the bimetallic member 42 thus causes disengagement thereof with the lug 4| carried by the latch arm 34. This accordingly causes the latch arm 34 to rotate in a counter-clockwise direction about its pivot 35, due to the potential energy stored in the coil spring 33, with the result that the wedgeshaped end 33 passes beneath the movable leg of the heat-responsive element l4, thus maintaining contacts l1 and I3 separated, as shown in Fig. 5, and thereby interrupting the circuit to both the lamp 23 and heater 25. Furthermore, repetitious cyclic operation of the relay 5 in a futile attempt to start a failed lamp is accordingly prevented and the useful operating life of the relay is preserved.

Upon replacement of the defective lamp 29 and the bimetallic element 42 having cooled due to interruption of the circuit to the heater, the lock-out latch 34 is moved to its latched or set position by the operator moving the finger piece 36 to the right, as seen in Figs. 1 and 4, thus causing -clockwise rotation of the latch arm 34 about its pivot 35 until the pin or lug 4| is again disposed on the side of the bimetallic member 42 and the spring 33 tensioned. Moreover, such manual movement of the latch arm 34 is in no way impaired since the pin 4| in the open position of the contacts i1 and II merely bears on the surface of the bimetallic strip 42. Even should it ride over on the opposite side, the lug 4| may be provided with a taper so as to allow ready movement of the latch arm 34 about its pivot in a clockwise direction while locking the latter against movement in a counter-clockwise direction until the bimetallic member 42 deflects out of engagement with the lug 4|, in the manner above described.

It thus becomes obvious to those skilled in the art that a starting relay for a fluorescent lamp is herein provided which operates with fidelity to start the lamp and which is economical to manufacture. Moreover, such relay performs its cyclic operation until a discharge is ultimately initiated in the lamp. Should the lamp have failed, however, then the relay operates only for a number of times corresponding to a predetermined period of time, after which the relay autnmaticah.

1y operates to disconnect or "lock-out" the defective lamp, thereby preserving the useful life of the relay. Upon replacement of the defective lamp, the relay is then reset by the person installing the new lamp and is ready again to perform its dual purpose as a starter and protective device.

Although one embodiment oi the present invention has been shown and described, still further modifications thereof may be made without departing i'rom the spirit and scope of the appended claims.

I claim: 1

1. A relay for starting an electric discharge lamp comprising a base, heat-responsive means carried by said base, an electric heater disposed in heat transfer relation to said heat-responsive means for causing deflection oi the latter upon the accumulation of heat therein, circuit con trolling means operable to open and close in response to deflection of said heat-responsive means due to heating and cooling thereof, and means automatically movable into a. position to prevent circuit closing operation of said circuit controlling means only upon the application of a potential to said electric heater for 'a predetermined period of time.

2. A relay for starting an electric discharge lamp comprising a base, heat-responsive means carried by said base, an electric heater disposed in heat transfer relation to said heat-responsive means, a pair of normally closed contacts for completing a circuit to said lamp and operable to open and interrupt said circuit upon heating of said heat-responsive element by said electric heater, and means movable into a position between said contacts to maintain the same in an open position only upon the application of a potential to said electric heater for a predetermined period of time. 4

3. A relay for starting an electric discharge lamp comprising a base,"heat-responsive means carried by said base, an electric heater disposed in heat transfer relation to said heat-responsive means for causing deflection of the latter upon the accumulation of heat therein, circuit controlling means operable to open and close in response to deflection of said heat-responsive means due to heating and cooling thereof, a tensioned member connected to said base, and a second heat-responsive means normally holding said member under tension and operable upon heating to deflect and allow movement of said tensioned member into a position to prevent circuit closing operation of said circuit controlling means upon the application of full line voltage to said heater for a predetermined period of time.

A relay f Sta ting an electric discharge lamp comprising a base, heat responsiv means carried by said base, an electric heater disposed in heat transfer relation to said heat-responsive means for causing deflection of the latter upon the accumulation of heat therein, a pair of nor mally closed contacts for completing a circuit to said lamp. and operable to open and interrupt said circuit upon heating of said heat-responin heat transfer relation to said heat-responsive sive element by said electric heater, a tensioned latch arm pivoted to said base, and a bimetallic element normally engaging said latch arm to prevent rotation thereof about its pivot and operable upon heating to deflect out of engagement and allow said latch arm to rotate to a position between said contacts to prevent closure or the latter upon the application 01' full line voltage to said electric heater for a predetermined period 01' time.

5. A relay for starting an electric discharge lamp comprising a base, heat-responsive means carried by said base, an electric heater disposed means for causing deflection of the latter upon the accumulation of heat therein, circuit controlling means operable tr open and close in response to deflection of said heat-responsive means due to heating and cooling thereof, a tensioned member connected to said base, a second heat-responsive means normally holding said member in a tensioned position and operable upon heating to deflect and allow movement of said tensioned member into a Position to prevent circuit closing operation of said circuit controlling means upon the application of full line voltage to said heater for a predetermined period 01 time, and means'for returning said tensioned member to its normally tensioned position upon cooling of said second heat-responsive means.

6. A relay for starting an electr c discharge lamp comprising a base, heat-responsive means carried by said base, an electric heater disposed in heat transfer relation to said heat-responsive means for causing deflection of the latter upon the accumulation of heat therein, a pair of normally closed contacts for completing a circuit to said lamp and operable to open and interrupt said circuit upon heating of said heatresponsive element by said electric heater, a tensioned latch arm pivoted to said base, a bi metallic element normally engaging said latch arm to preventrotation thereof about its pivot and operable upon heating to deflect out of engagement and allow said latch-arm to rotate to a position between said contacts to prevent closure of the latter upon the application oi full line voltage to said electric heater for a predetermined period of time, and a finger-piece extension on said latch arm for returning the same to its normally tensioned position upon cooling of said bimetallic element.

7. A relay for starting an electric discharge lamp comprising a base, heat-responsive means carried by said base, an electric heater operable to initially heat said heat-responsive means and cause rapid deflection thereof upon the application of approximately full line voltage to said heater and to maintain said heat-responsive means in a deflected position upon continued application of lamp voltage to said heater, a pair of normally closed contacts for completing a circuit to said lamp, said contacts being cylically operable to open and cause the initiation of a discharge in said lamp upon initial deflection of said heat-responsive means and to remain open upon the application of lamp voltage to said heater, and said contacts being operable to close again upon cooling of said heat-responsive means in the event a discharge is not immediately initiated in said lamp with attendant repetitious operation of said contacts until lamp voltage is finally applied to said heater; and a member automatically movable into a. position between said contacts to maintain the latter in an open position upon continued cyclic opening and closing of said relay contacts for a predetermined number 01' times.

8. A relay for starting an electric discharge lamp comprising a base, heat-responsive means carried by said base, an electric heater operable to initially heat said heat-responsive means and cause rapid deflection thereof upon the application of approximately full line voltage to said heater and to maintain said heat-responsive means in a deflected position upon continued application of lamp voltage to said heater, a pair of normally closed contacts for completing a circuit to said lamp, said contacts being cyclically operable to open and cause the initiation of a discharge in said lamp upon initial deflection oi said heat-responsive means and to remain open upon the application of lamp voltage to said heater with continued deflection of said heat-responsive means, and said contacts being operable to close again upon cooling of said heat-responsive means in the event a discharge is not immediately initiated in said lamp with attendant repetitious operation of said contacts until lamp voltage is flnally applied to said heater; a tensioned latch arm pivoted to said base, and a bimetallic element normally engaging said latch arm to prevent rotation thereoi about its pivot and operable upon heating to deflect out of engagement and allow said latch arm to rotate to a position between said contacts to prevent closure of the latter upon the application of full line voltage to said electric heater for a. predetermined period of time.

9. A relay for starting an electric discharge lamp comprising a base, heat-responsive means carried by said base, an electric heater operable to initially heat said heat-responsive means and cause rapid deflection thereof upon the application of approximately full line voltage to said heater and to maintain said heat-responsive means in a deflected position upon continued application of lamp voltage to said heater, a pair of normally closed contacts for completing a circuit to said lamp, said contacts being cyclically operable toopen and cause the initiation of a discharge in said lamp upon initial deflection of said heat-responsive means and to remain open upon the application of lamp voltage to said heater with continued deflection of said heat-responsive means, and said contacts being operable to close again upon cooling oi said heat-responsive means in the event a discharge is not immediately initiated in said lamp with attendant repetitious operation oi said contacts until lamp voltage is flnally applied to said heater; a tensioned latch arm pivoted to said base, a bimetallic element normally engaging said latch arm to prevent rotation thereof about its pivot and operable upon heating to deflect out of engagement and allow said latch arm to rotate to a position between said contacts to prevent closure oi the latter upon the application oi iull line voltage to said electric heater ior a predetermined period oi time, and an extension on said latch arm engageable by the flnger for returning said latch arm to its normally tensioned position upon cooling of said bimetallic element.

10. A relay ior starting an electric discharge lamp comprising a base, heat-responsive means carried by said base, an electric heater disposed in heat transier relation to said heatresponsive means for causing deflection oi the latter upon the accumulation oi heat therein, circuit-controlling means operable to open and close in response to deflection oi said heat-responsive means due to heating and cooling thereof, means to prevent circuit-closing operation oi said circuit-controlling means only upon the application of a potential to said electric heater for a predetermined period oi time, and means ior restoring said last-mentioned means to its normal condition iollowing operation of the latter to circuit-closing preventing position.

CHARLES H. HODGKINS. 

